Influence of the Glycemic Index of Pre-exercise Meals in Sports Performance: A Systematic Review

Abstract

Introduction: Carbohydrate (CHO) is essential for physical exercise. Some strategies for improving performance are based on the manipulation of the glycemic index (GI) of this nutrient during pre-exercise. Although several studies have been conducted on this subject, the use of low or high GI in a pre-exercise meal to improve performance remains undefined. Methods: In the present systematic review, the Pubmed (Medline) and Virtual Health Library databases were searched for randomized clinical trials conducted with healthy, physically active adults between 2006 and 2019, in which performance in addition to blood biochemical parameters, substrate utilization, body composition, perception of effort, and gastrointestinal symptoms were evaluated. The identified articles were independently and blindly evaluated by two authors, and any disagreements were resolved by a third investigator. Results: Five of the sixteen studies reviewed found differences in performance; of these, four were with low GI intervention. Few studies showed modifications in blood lactate and glucose levels beyond fatty free acid oxidation. No differences could be seen in the other parameters. The results as well as the methodologies used were heterogeneous; therefore, there are no clear advantages in determining the specific GI of the pre-exercise meal. Conclusions: There is no evidence that the pre-exercise meal GI influences performance. The heterogeneity of the studies precludes further conclusions.

The 4R’s Framework of Nutritional Strategies for Post-Exercise Recovery: A Review with Emphasis on New Generation of Carbohydrates

“…In addition, Amano et al (2019) demonstrated that the ingestion of a 6.5% w / v isomaltulose drink plus electrolytes (Na + , Ca 2+ , Mg 2+ and K + ) may optimize post-exercise rehydration without affecting heat loss responses in healthy and physically active young men [ 54 ]. Therefore, current evidence suggests that low glycemic and low insulinemic properties of non-starch slowly digestible carbohydrates appear of a particular interest in sports nutrition and cognitive performance [ 55 , 56 ]. Further research is still needed due to the heterogeneity of the studies, and reports of negligible effects when conditions of the athletes are matched for carbohydrates and energy [ 18 ].…”

The microbiota-gut-brain-immune interface in the pathogenesis of neuroinflammatory diseases: a narrative review of the emerging literature

“…Transmitting electrochemical signals between neurons and to effector sites, neurotransmitters can act as hormones, promoting function and health in peripheral tissues including the brain ( 47 , 48 ). Many neurotransmitters are also produced by gut microbiota including γ-aminobutyric acid (GABA), norepinephrine, epinephrine, dopamine, and acetylcholine ( 20 , 49 , 50 ). While these microbial neurotransmitters clearly play a role in the gut (see Tables 1 , 2 ), in proximal regions, and likely in circulation, it is unclear if all or some of these interact with the CNS in sufficient concentrations to have a meaningful effect; however, they can exert an effect via the ENS including the vagus nerve ( 51 , 52 ).…”